Arc protecting device



Jan. 2, 1940. E. 1. M CLURE ARC PROTECTING DEVICE Filed March 24, 1938 Inventor EAEL L. M C'LUEE Allorney Patented Jan. 2, 1940 UNITED STAES PATENT OFFIQE ARC PROTECTING DEVICE Application March 24,

4 Claims.

My invention relates to devices for use in the construction of overhead trolley systems and particularly to section insulators for use in such systems.

One object of my invention is to reduce the destruction of certain parts which are made of insulating material and subject to burning as the result of breaking the current supplied to a vehicle passing across the device.

I obtain the above objects and others hereinafter disclosed by the construction, combination and relation of parts described in the following specification and shown in the accompanying drawing, in which- Fig. l is a side view of my invention.

Fig. 2 is an enlarged side view of one portion of my invention.

Fig. 3 is a face view of Fig. 2.

Fig. 4 is a top view of Figs. 2 and 3.

Fig. 5 is a top view of the right-hand end of Fig. 1.

In the device shown in Figs. 1 and 5, the same comprises end castings i and 2 held in spaced and insulated relation by a tension member 3 made of or provided with an outer covering 4 of insulat ing material and a compression member 5 of insulating material and a bridging member 6 of insulating material, the latter held in place by removable metal clips 1.

The removable feature of the clips 1 makes the replacement of the bridging member 6 and clips I very easily and quickly accomplished at a small expense.

When a current collector 8 moves across the device in the direction of the arrow an arc is sure to form at the point A where the collector 8 breaks contact with the clip I if the vehicle operator has his controller set to the on position. Under such condition the arc may be as much as 200 amperes or more at 500 volts which means a large amount of energy in the form of heat is dissipated at the point A and adjacent thereto.

When such an arc occurs it is accompanied by a flame of considerable length and heat and this flame rises and envelops the insulating covering l and may attack the member 5, but the member 4 receives the greatest destructive effect of the flame.

The insulation t and 5 in the form of the device shown is usually of indu-rated or vulcanized fibre or of fibrous material impregnated with Bakelite or other resins or with gums such as shellac or copal and as these materials are largely of vegetable or animal origin they are easily 1938, Serial No. 197,923

affected by the heat and flame from the arc. Woo-d may be used also as the insulating material in a device, for the purpose described but it also is subject to burning or charring.

To replace a member 4 is expensive and a 5 time taking process as the device must be removed from the line and the work done at a shop; therefore, I provide means to protect the members 4 and 5 or their equivalent from the burning eifect of the arc and its flame.

To accomplish this result, I mount on the insulator adjacent the end member with which the current collector first contacts in crossing a device, means for protecting the insulation adjacent such end member from the effect of the 15" arc and the flame thereof. In the device shown in Figs. 1 and 5 the protecting member B comprises a pair of clamping members 9, each provided with registering grooves II] to form the I opening H and also formed with the registering 20 grooves l2 to form the opening 3. The members 9 are also provided Wtih registering openin s id to receive the through bolt i5. The axis of the openings l4 being disposed at right angles to the axes of the openings l I and 13.

The members 9 when assembled on the rods 4 and 5 and the bolt I 5 drawn tight form a space l6 between the parts 9 for adjustment. The parts 9 are provided with flanges I! which project laterally somewhat beyond the adjacent portions of the end casting l.

The protecting means B is placed in position on the members 4 and 5 and spaced from the end member I as shown at C. The means B being thus insulated from the member I, the tendency for the are formed at the point A to rise and continue from the member B is quite remote. The flame from the are at the point A, however, will rise but the member B will shield the insulation 4 and 5 from the severe burning efiect thereof.

The member B is of a considerable mass and the tendency thereof seems to be to reduce somewhat the severity of the are at A and to reduce the magnitude of the flame or its burning e1- feet but by no means eliminating the arc. Just why this should be, I am not in a position to say, but I am basing the beneficial results upon actual experience.

The member B may be made from a so-called non-arcing metal or brass which is an alloy, as for instance, 40% to 70% zinc and the balance copper.

The member B is placed close to the member I therefore the heat and flame does not pass through the space C and attack the insulation 5. The member B may be made to extend along the length of the insulator as far as deemed necessary for shielding the insulation but its length should be as small as possible.

The mass of the member B may have a cooling eflect upon the arc and its flame which would naturally reduce the burning effect and length of the arc and flame.

The member B may be of other shape to meet requirements but in each case I prefer the member to be insulated from the end member and not in electrical connection with the trolley wire l8 which is held in place by the screws IS. The device B shown in the drawing may be said to have a cross-section resembling an I beam having a split web and flanges ll.

If desired the member B may be made to clamp on to only the member 3 and this would be the construction if the section insulator be made with a single insulating member between the end members for holding the end members in spaced and insulated relation.

The member B is preferably made of a metal as it withstands the heat and flame from the arc and such of the are as may jump to the member B, much better than other materials, such as asbestos sheet, asbestos fibre mixed with lime or plaster, etc, vitreous materials such as porcelain or glass, slate, etc., although such materials may be used as a protection to the insulating members 3 and 5, they do not, however, have the capacity apparently in checking the magnitude of the arc and flame which metal seems to possess.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A flame protector for application to the tension member of a section insulator comprising a pair of metallic members for attachment to the tension member adjacent an end thereof to protect the tension member from a flaming arc, an opening through the protector to receive the ten sion member, means transversely disposed to the axis of the opening to hold the members in position on the tension member, each member having a cross-section approximately that of a T bar in a transverse plane parallel to the axis of the opening and the protector having a crosssection in the same plane approximately an I beam.

2. The combination with a section insulator having metallic end members to receive trolley wires and tension means to hold the end members in spaced and insulated relation and also having means associated with the end members to protect the end members from burning due to an are produced by a passing current collector, of metallic means associated with the tension means and held in spaced and insulated relation relative to an end member and on which the flame from the arc may impinge and to shield the tension means from the flame of the arc from the passing current collector, the said metallic shielding means positioned out of contact with the passing current collector.

3. The combination with a section insulator having spaced end castings of metal to receive and hold trolley wire ends and held in spaced and insulated relation by an insulating member, of metallic means attached to the insulating member adjacent one end member and spaced from the end member and so positioned as to avoid being engaged by a passing current collector, the said means adapted to receive thereon the flame from an arc produced by the passing current collector as it breaks contact with the end member.

i. A protecting device for a section insulator having metallic end members held in spaced and insulated relation by an insulating tension member, comprising two counterpart bodies of metal, each body having means to cooperate with like means on the other body whereby the device may be adjustably mounted on the tension member, means to hold the bodies secured to the tension member in adjusted relation to the end member, the device adapted to receive the flame from an are produced by a passing current collector and protect the tension member therefrom without contacting with the current collector.

EARL L. MCCLURE. 

